Method of surface processing

ABSTRACT

A surface is processed by a method comprising: supplying a first gas, e.g. TEOS, through a passage disposed near a surface of a wafer, the first gas being insusceptible to heating by microwave; and supplying a second gas, susceptible to heating be microwave, e.g., H 2 O, through a passage disposed near the wafer surface. A microwave generating unit disposed near the wafer surface irradiates TEOS supplied from the first supplying passage and H 2 O gas supplied from the second gas supplying passage with microwave, selectively heating only H 2 O so that TEOS reacts with H 2 O to form an SiO 2  film on the wafer surface. The inventive method enables precise control of the CVD reaction to form a thin film having good step coverage.

This application is a divisional of application Ser. No. 08/711,330filed Sep. 6, 1996 now U.S. Pat. No. 5,868,849.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a surface processing device and amethod of processing a surface. It particularly relates to a surfaceprocessing device and a method of processing a surface which contemplateimprovement in processing a surface of an object to be processed.

2. Description of the Background Art

Conventionally in the process for manufacturing semiconductor devices,various types of surface processing are performed, typically includingfilm forming and etching. The film forming process includes the CVDmethod and sputtering.

An example of a conventional plasma CVD system will now be describedwith reference to FIG. 5.

A conventional plasma CVD system 300 has an electrode 306 and a holderelectrode 308 contained opposite to each other within an evacuatedcontainer 304 which is evacuated by an evacuating device 312. Holderelectrode 308 is grounded. Mounted on holder electrode 308 is asubstrate 302 to the surface of which film forming process is applied.Substrate 302 is heated, for example, by a heater 310 within holderelectrode 308.

A raw material gas 320 is introduced into evacuated container 304 viagas introducing portion 314 communicating with electrode 306. As rawmaterial gas 320, SiH₄ (silane) +H₂O is used, and recently, TEOS(tetraethoxysilane) +H₂O or the like has come to be used in view ofprocessing at lower temperature and for planarization of silicon oxidefilms.

In plasma CVD system 300, gas introducing portion 314 is supplied withTEOS from a gas source 322 and H₂O from a gas source 324. Furthermore,mass flow controllers 326 and 328 are provided at supplying passages ofTEOS and H₂O, respectively, and a heater 330 for vaporizing TEOS is alsoprovided at the TEOS supplying passage.

Radio frequency (RF) power is supplied to the space between electrode306 and holder electrode 308 from an RF generator 318 via a matching box316. A continuous sign wave is used for the RF power and its frequencyis generally 13.56 MHz.

In such a plasma CVD system, when raw material gas 320 as describedabove is introduced into evacuated container 304 to obtain a degree ofvacuum, for example, of several hundred mTorr within evacuated container304 while RF power is supplied to electrode 306 from RF generator 318,RF electric discharge is generated between electrodes 306 and 308,causing plasma 332 therebetween.

At that time, electrons are trapped in a blocking capacitor, which isgenerally contained in matching box 316, so that electrode 306 isnegatively charged. This causes positive ions in plasma 332 toaccelerate toward and collide against electrode 306 and electrons arethereby generated to maintain plasma 332.

Thus, due to plasma 332, raw material gas 320 is activated and chemicalreactions proceed whereby a silicon oxide (SiO₂) film is formed on asurface of substrate 302.

The reaction between the TEOS and H₂O described above can be expressedby the following chemical formulas:

i) Si(OC₂H₅)₄+H₂O→Si(OC₂H₅)_(4-n)(OH)_(n)+C₂H₅OH  (hydrolysis reaction)

ii) Si(OC₂H₅)_(4-n)(OH)_(n)→SiO_(m)(OH)_(j)(OC₂H₅)_(k)+H₂O  (dehydratingcondensation reaction)

iii) SiO₂+H₂O+C₂H₅OH

TEOS=Si(OC₂H₅)₄

silanol=Si(OC₂H₅)_(4-n)(OH)_(n)

silicon polymer=SiO_(m)(OH)_(j)(OC₂H₅)_(k)

In the system of reaction between TEOS and H₂O, silanol is firstproduced by the hydrolysis reaction expressed by chemical formula (i).Then, by the dehydrating condensation reaction expressed by chemicalformula (ii), silicon polymer having an appropriate molecular weight isproduced from the silanol as an intermediate. The silicon polymeradheres to a surface of an object to be processed and is fluidized torealize a planarized film formed on the substrate surface. Thereafter,as expressed by chemical formula (iii), the silicon polymer alsodehydrates to produce SiO₂ and thus SiO₂ film is formed on the substratesurface.

However, in the reactions in the above plasma CVD system, since achemical reaction is caused by electrons of several eV, the molecules ofthe raw material gases are decomposed into many kinds of molecules. Thispractically makes it difficult to selectively cause only the abovedesired reactions.

In forming a SiO₂ film by reaction between TEOS and H₂O, it is importantto produce silanol by reacting TEOS, the molecular structure of which iskept intact, with H₂O maintained at high temperature.

However, while the decomposition of the new material gases by plasmapartially excites reaction (i), Si and SiO produced by decomposition ofTEOS directly reacts with O produced by decomposition of H₂O, forexample, causing a reaction dominantly producing SiO₂, rather thansilanol, as the intermediate. Thus, it is not practically ensured thatthe films formed are adequately planarized by silicon polymer.

Furthermore, in the above plasma CVD system, since silanol is lessproduced and SiO₂ in gas phase dominantly adheres to the substratesurface, flatness of the films cannot be achieved without keeping thesubstrate at a low temperature of at most 120° C. and restraining thedehydrating condensation rate of the silanol.

Thus, since a SiO₂ film thus formed on a substrate maintained at lowtemperature has not experienced adequate reaction, it contains a largeamount of OH group and has shortcomings such as large leakage currentand low dielectric strength.

Furthermore, when heat treatment (300° C.-400° C.) is performed afterthe film formation to improve film quality, volumetric shrinkage iscaused and thus tensile stress is caused, resulting in cracks or thelike in the film.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a surface processingdevice and a method of processing a surface capable of preciselycontrolling CVD reaction to form thin films with good step coverage,which is required, for example, for manufacturing semiconductor devices.

Another object of the present invention is to provide a surfaceprocessing device and a method of processing a surface capable ofprecisely etching a surface of an object to be processed inmanufacturing semiconductor devices.

A surface processing device according to the present invention processesa surface of an object to be processed in an atmosphere under theatmospheric pressure. It includes: a first gas supplying passagedisposed near the surface of the object to be processed for supplying afirst gas insusceptible to heating by electromagnetic wave; a second gassupplying passage disposed near the surface of the object to beprocessed for supplying a second gas susceptible to heating byelectromagnetic wave; and an electromagnetic wave generating unitdisposed near the surface of the object to be processed for irradiatingthe first gas supplied from the first gas supplying passage and thesecond gas supplied from the second gas supplying passage withelectromagnetic wave and selectively heating only the second gas tocause reaction between the first gas and the second gas, therebyprocessing the surface of the object to be processed.

Preferably, a plurality of the first gas supplying passages and aplurality of the second gas supplying passages are alternately provided.Still preferably, the electromagnetic wave generating unit is amicrowave generating unit.

When a gas containing TEOS is used as the first gas and a gas containingH₂O is used as the second gas in the above surface processing device,for example, it is possible to selectively heat only the second gas,H₂O, near the surface of the object to be processed by microwavegenerated from the electromagnetic wave generating unit.

Thus, since dissociation of molecules of the first gas, i.e., TEOS, ishardly caused, it is ensured that the following reactions are caused:

i) Si(OC₂H₅)₄+H₂O→Si(OC₂H₅)_(4-n)(OH)_(n)+C₂H₅OH  (hydrolysis reaction)

ii) Si(OC₂H₅)_(4-n)(OH)_(n)→SiO_(m)(OH)_(j)(OC₂H₅)_(k)+H₂O  (dehydratingcondensation reaction)

iii) SiO₂+H₂O+C₂H₅OH

TEOS=Si(OC₂H₅)₄

silanol=Si(OC₂H₅)_(4-n)(OH)_(n)

silicon polymer=SiO_(m)(OH)_(j)(OC₂H₅)_(k)

Consequently, it is ensured that silanol is produced as the intermediateand an SiO₂ film having adequate flatness can be formed. Furthermore,since the SiO₂ is continuously fired during the film formation, an SiO₂film with small leakage current and good dielectric strength can beformed.

Furthermore, when a gas containing F₂ gas is used as the first gas and agas containing H₂O is used as the second gas, only the second gas, H₂O,can be selectively heated by microwave generated from theelectromagnetic wave generating unit, causing the following reactionwithout using HF vapor:

F₂+H₂O→HF+O₂.

Thus, oxide films can be selectively etched safely, using HF anhydride.

Furthermore, the above surface processing device is provided with a gasmixing chamber for mixing the first gas supplied from the first gassupplying passage with the second gas supplied from the second gassupplying passage at the region of the outlets of the first and secondgas supplying passages, the gas mixing chamber being provided with anelectromagnetic wave generating unit. In this configuration, it ispossible to cause the above reactions within the gas mixing chamber.

Still preferably, in the above surface processing device, the first andsecond gas supplying passages have their routes defined at their outletsby dielectric members capable of transmitting electromagnetic wave, anelectromagnetic wave generating unit is provided in the region of thefirst and second gas supplying passages partitioned by the dielectricmembers, and ceramic, quarts or the like is used for the dielectricmembers.

With this structure, when there is a high reactivity between the firstgas and the second gas, only the second gas can be preheated using theelectromagnetic wave generating unit and thereafter the first and thesecond gases can be mixed to cause the above film forming and etchingreactions or the like near the surface of the object to be processed.

A method of processing a surface according to the present inventionincludes, in a system including a supplying port disposed near a surfaceof an object to be processed for supplying a first gas insusceptible toheating by electromagnetic wave and a second gas susceptible to heatingby electromagnetic wave, in an atmosphere under the atmosphericpressure, the steps of: selectively heating only the second gas byirradiating the first and second gases with electromagnetic wave; andprocessing the surface of the object to be processed by reaction betweenthe first gas and the heated second gas.

Still preferably, the selective heating step is performed with the firstgas and the second gas being separated. Still preferably, the first gascontains a first reactive gas which reacts on the second gas and thefirst carrier gas which does not react on the second gas, and the secondgas contains a second reactive gas which reacts on the first gas and asecond carrier gas which does not react on the first gas.

In the method of processing a surface described above, when TEOS as anorganosilane compound is used as the first reactive gas, H₂O, is used asthe second reactive gas and a noble gas is used as the first and secondcarrier gases, only the second reactive gas, H₂O, can be selectivelyheated, for example, by microwave generated from the electromagneticwave generating unit.

Therefore, dissociation of molecules of the first reactive gas, TEOS, ishardly caused and thus the reactions i), ii) and iii) described aboveare surely performed.

As a result, it is ensured that silanol is produced as the intermediateand an SiO₂ film having good flatness can be formed. Furthermore, sincethe SiO₂ is continuously fired during the film formation, a SiO₂ filmwith small leakage current and good dielectric strength can be formed.

Furthermore, in the method of processing a surface described above, whena noble gas, such as argon and xenon, the mass numbers of which arelarger than that of H₂O, is used as the second carrier gas, energy lossdue to collision of the heated H₂O molecules is reduced so that H₂O maynot be cooled and can thus reach the reaction space near the object tobe processed.

On the other hand, when a gas containing F₂ gas is used as the first gasand a gas containing H₂O is used as the second gas, only the second gas,H₂O, can be selectively heated by microwave generated from theelectromagnetic wave generating unit, causing the following reactionwithout using HF vapor:

F₂+H₂O→HF+O₂.

Thus, it is possible to selectively etch an oxide film safely, using HFanhydride.

Furthermore, in the above method of processing a surface, the selectiveheating step is performed with the first gas being separated from thesecond gas.

This allows a stable, selective heating step even when there is a highreactivity between the first gas and the second gas.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a CVD system according to a firstembodiment.

FIG. 2 is a perspective view of the structure of a gas separatingportion.

FIG. 3 is a cross sectional view of a modification of the CVD systemaccording to the first embodiment.

FIG. 4 is a cross sectional view of an etching system according to asecond embodiment.

FIG. 5 is a schematic view of a structure of a conventional plasma CVDsystem.

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment]

An embodiment in which a surface processing device according to thepresent invention is applied to a single-wafer-processing atmosphericpressure CVD system will now be described with reference to FIGS. 1-3.

Referring now to FIG. 1, the structure of an atmospheric pressure CVDsystem 100 in cross section will be described. Provided in a chamber 101is a holder 102 which attracts a wafer 1 by evacuation and is internallyprovided with a heater and a cooler. Provided under holder 102 are areactive gas lead-through port 109 and a gas reacting chamber 108.

Provided under gas reacting chamber 108 are gas A supplying passages 106for supplying a gas A insusceptible to heating by electromagnetic waveto gas reacting chamber 108 and gas B supplying passages 107 forsupplying a gas B susceptible to heating by electromagnetic wave to gasreactive chamber 108 such that these supplying passages are partitionedby diaphragms 105, thus providing a gas separating portion 104 in whichgas A supplying passages 106 and gas B supplying passages 107 arealternately disposed.

As for the details of the structure of gas separating portion 104, asshown in the perspective view in FIG. 2, an electromagnetic inductiontube 111 is provided for introducing electromagnetic wave 500 radiatingfrom an electromagnetic wave generating unit 103 to gas reacting chamber108, and the dimensions of gas separating portion 104 according to thepresent invention are approximately L=at most 40 cm, W=at most 40 cm andH=at most 10 cm.

Preferably, the distance (S) between wafer 1 and gas reacting camber 108is approximately 3 mm.

Furthermore, when there is a high reactivity between gas A and gas B, itis effective to use an atmospheric pressure CVD system 150 shown in FIG.3.

Atmospheric pressure CVD system 150 shown in FIG. 3 has the samestructure as atmospheric pressure CVD system 100 shown in FIG. 1, exceptfor the structure of gas reacting chamber 108.

In gas reacting chamber 108 of atmospheric pressure CVD system 150, gasA supplying passages 106 and gas B supplying passages 107 are alsoprovided such that these passages are partitioned by dielectricdiaphragms.

Dielectric diaphragms 112 are formed of a material capable oftransmitting electromagnetic wave generated from electromagnetic wavegenerating unit 103, such as quarts or ceramic.

Thus, in this structure, gas A is not mixed with gas B in gas reactingchamber 108, only gas B is selectively heated by electromagnetic wave200 radiating from electromagnetic wave generating unit 103, and gas Awill not react with gas B until they reach reactive gas lead-throughport 109.

Both atmospheric pressure CVD systems 100 and 150 shown in FIGS. 1 and3, respectively, are provided with a gas exhaust passage 114 aboveholder 102 for exhausting gas.

An example of SiO₂ film formation onto wafer 1 using atmosphericpressure CVD system 100 or 150 will now be described.

The conditions of gas A, gas B and atmospheric pressure CVD system 100are as follows:

Gas A

First reactive gas: TEOS (tetraethoxysilane) with a flow rate of 0.5 SLM(Standard Liter per Minute)

First carrier gas: Xe with a flow rate of 5.0 SLM

Gas B

Second reactive gas: H₂O with a flow rate of 1.0 SLM

Second carrier gas: Xe with a flow rate of 5.0 SLM

Electromagnetic Wave

Microwave with a microwave power of 200 W

Temperature of holder: 350° C.

When gas A reacts with gas B under the above conditions, the followingreactions are caused:

i) Si(OC₂H₅)₄+H₂O→Si(OC₂H₅)_(4-n)(OH)_(n)+C₂H₅OH  (hydrolysis reaction)

ii) Si(OC₂H₅)_(4-n)(OH)_(n)→SiO_(m)(OH)_(j)(OC₂H₅)_(k)+H₂O  (dehydratingcondensation reaction)

iii) SiO₂+H₂O+C₂H₅OH

TEOS=Si(OC₂H₅)₄

silanol=Si(OC₂H₅)_(4-n)(OH)_(n)

silicon polymer=SiO_(m)(OH)_(j)(OC₂H₅)_(k)

The characteristics of the film formed, when the film thickness=0.1 μmand the electric field applied=6 MV/cm are as follows wherein the term“BHF” denotes buffered hydrofluoric acid, i.e., an aqueous solution of amixture of hydrogen fluoride (HF) and ammonium fluoride (NF₄F):

Growth rate of SiO₂: 0.5 μm/min

Flatness: ±2%

Film quality: refractive index n=1.50

Film stress (tension): 0.5×10⁹ dyn/cm²

6:3 BHF (etching rate): 0.12 μm/min

Breakdown electric field: 9.5 MV/cm

Leakage current: 200 pA/cm²

The reason why only gas B, H₂O, is heated by microwave while thetemperature of TEOS is not increased in reacting H₂O with TEOS is asfollows: in order to provide adequate reactivity to H₂O, the temperatureof H₂O need be increased to at least 600° C. On the other hand, when thetemperature of TEOS is increased to at least 500° C., the followingreaction proceeds by pyrolysis reaction:

Si(OC₂H₅)₄→SiO₂+C₂H₅·OH.

In other words, when the temperature of TEOS is increased, the reactionto produce SiO₂ proceeds in gas phase so that the reaction to producesilanol, which is essential to planarizing the film, is restrained.Furthermore, the composition of SiO₂ at the film surface, which shouldbe mainly composed of silanol polymer, includes SiO₂ in solid phase,resulting in degradation in fluidity and hence in flatness.

Therefore, in order to obtain adequate flatness, it is important thatthe temperature of H₂O only is increased while that of TEOS is notincreased.

The reason why H₂O is heated by microwave is as follows: in order toheat only H₂O while TEOS is not heated, gas introducing paths of gas Aand gas B may be separated from each other, for example, so that H₂O canbe heated at the H₂O introducing path. However, when the heating portionis distant from the wafer surface and the wafer surface is maintained atlow temperature, the heated H₂O is cooled between the wafer surface andthe H₂O heating portion and the temperature of H₂O required at the wafersurface cannot be obtained.

In order to avoid this, the entire H₂O gas passages up to the wafersurface may be maintained at high temperature. However, this allows thetemperature of TEOS introduced onto the wafer surface to increase andthe requirement that only H₂O is heated cannot be satisfied.

Furthermore, the temperature of a wafer surface can be determined by thecharacteristic of the film formed on the wafer. For example, thetemperature of the wafer surface must not exceed 450° C. in formingfilms in the process for aluminum multilayer interconnections.

Thus, heating by microwave is considered to be optimal as a method ofonly increasing the temperature of H₂O at or near the wafer surface.

In the present embodiment, as described above, since the temperature ofH₂O only is increased to 600° C.-800° C. using microwave, dissociationof TEOS molecules is hardly caused and thus the formation reaction ofthe silanol required is adequately caused. Thus, an SiO₂ film with asuperior flatness can be formed as compared with those conventionallyformed.

Furthermore, since silanol is selectively formed to form an SiO₂ filmand thus there is nothing to prevent flow of the silanol contained inthe film being formed, the surface of the film being formed is mainlyformed of polymer having a molecular weight which allows flow of thepolymer even when the dehydrating condensation weight at the wafer isincreased. Thus, enhanced flatness can be realized under a film formingcondition of a temperature of 300° C.-400° C. Furthermore, since theSiO₂ film is continuously fired at a temperature of as high as 300°C.-400° C. during the forming of the SiO₂ film, a film with smallleakage current and good dielectric strength can be formed with lowstress.

While an example in which TEOS is used as the first reactive gas hasbeen described, the silane compound and the organosilane compounds shownin Table 1 may be used to obtain a similar effect.

TABLE 1 silane SiH₄ silane compound Si₂H₆ disilane Si₃H₈ trisilaneSi₂H₂Cl₂ dichlorosilane organosilane Si(OC₂H₅)₄ TEOS compound Si(OCH₃)₄tetraethoxysilane TMOS tetramethoxy silane Si(OCH₃)₂(OC₄H₉)₂ DADBSdiacetoxydibutoxy silane

HMDS hexamethyl disiloxane

HEDS hexaethyl disiloxane Si(OC₂H₅)₃H triethoxysilane

TMCTS tetramethylcyclo trisiloxane

Furthermore, while Xe has been used as the second carrier gas for H₂O,N₂ (the mass number=28) is often used as a carrier gas for H₂O in aconventional CVD system. H₂O molecules heated by microwave, whencolliding against the carrier gas molecules, will lose their energy andthus the H₂O molecules are cooled. However, it is physically apparentthat when H₂O molecules collide against molecules having a relativelylarger mass number, the H₂O molecules lose less energy per onecollision, and thus are hard to cool.

Thus, if a gas having a mass number larger than that of H₂O, 18, is usedas the carrier gas, the heated H₂O molecules are not cooled and thusreach the reaction space so that the heating of H₂O by microwave iseffectively used. Thus, while Xe having a mass number of 131 has beenused in the present embodiment, Ar having a mass number of 40 can alsobe used.

Furthermore, while a signal-wafer-processing atmospheric pressure CVDsystem is used in the first embodiment, a batch-processing CVD system ora CVD system which continuously processes wafers may be used to obtainsimilar function and effect.

[Second Embodiment]

An example in which a surface processing device according to the presentinvention is applied to an etching system will now be described withreference to FIG. 4. FIG. 4 shows the structure of an etching system 250in cross section.

Provided within a chamber 201 is a holder 202 which supports a wafer 1.Provided above holder 202 are a reactive gas lead-through port 213 and agas reacting chamber 208.

Provided above gas reacting chamber 208 are gas A supplying passages 206for supplying a gas A insusceptible to heating by electromagnetic waveto gas reacting chamber 208 and gas B supplying passages 207 forsupplying a gas B susceptible to heating by electromagnetic wave to gasreacting chamber 208 such that these passages are partitioned bydiaphragms 205, thus providing a gas separating portion 204 with gas Asupplying passages 206 and gas B supplying passages 207 alternatelydisposed.

In etching system 250 also, gas A supplying passages 206 and gas Bsupplying passages 207 are partitioned up to reactive gas lead-throughport 213 by diaphragms 212 formed of a dielectric material within gasreacting chamber 208, and an electromagnetic wave generating unit 203for radiating electromagnetic wave 200 is provided at gas reactingchamber 208. Dielectric diaphragms 212 are formed of quarts, ceramic orthe like.

Provided below chamber 201 is a removal unit 215 for externallyexhausting the gas sent from gas A supplying passages 206 and gas Bsupplying passages 207.

In the above etching system 250 also, gas B can be selectively heated ingas reacting chamber 208 by irradiating gas A and gas B withelectromagnetic wave 200.

A specific example in which the above etching system 250 is used to etchan oxide film on a surface of wafer 1 will now be described.

The conditions of gas A, gas B and etching system 250 are as follows:

Gas A: F₂ with a flow rate of 1.0 SLM

Gas B: H₂O with a flow rate of 0.1 SLM

Electromagnetic Wave: microwave with a microwave power of 20 W

Temperature of wafer: 100° C.

When gas A reacts with gas B under the above conditions, the followingreaction is caused:

F₂+H₂O→HF+O₂.

The result of the etching is as follows: the etching rate is 1.0 μm/minfor a BPSG film and 0.01 μm/min for a thermal oxide film.

Thus, selective etching of oxide films by using HF anhydride can beapplied. Since oxide films can be selectively etched without using HFvapor, the gas introducing passages need not be corrosion-resistant.This allows safe, selective etching of oxide films.

The reason why the temperature of H₂O only is increased while that of F₂is not increased is that the above reaction fails to materialize whenthe temperature of H₂O is low and that the above reaction materializeswhen the temperature of H₂O is at least 400° C.

On the other hand, when the temperature of F₂ is increased, F radicalsare produced and the pipes for the gas introduction system areundesirably eroded.

Thus, it becomes possible to cause the above reaction safely byselectively increasing the temperature of H₂O.

In a surface processing device according to the present invention, whena gas containing TEOS is used as the first gas and a gas containing H₂Ois used as the second gas, only the second gas, H₂O, can be selectivelyheated near a surface of an object to be processed by microwavegenerated from an electromagnetic wave generating unit. Consequently,since dissociation of molecules of the first gas, TEOS, is hardlycaused, it is ensured that silanol is produced as an intermediate andthus an SiO₂ film having good flatness can be formed. Furthermore, sincethe SiO₂ is continuously fired during the film formation, a SiO₂ filmwith small leakage current and good dielectric strength can be formed.

Furthermore, when a gas containing F₂ gas is used as the first gas and agas containing H₂O is used as the second gas, only the second gas, H₂O,can be selectively heated by microwave generated from theelectromagnetic wave generating unit, allowing selective etching ofoxide films using HF anhydride rather than HF vapor.

In the method of processing a surface according to the presentinvention, when TEOS as an organosilane compound is used as the firstreactive gas, H₂O is used as the second reactive gas and a noble gas isused as the first and second carrier gases, only the second reactivegas, H₂O, can be selectively heated, for example, by microwave generatedfrom the electromagnetic wave generating unit. Consequently, sincedissociation of molecules of the first reactive gas, TEOS, is hardlycaused, it is ensured that silanol is produced as an intermediate andthus a SiO₂ film having good flatness can be formed. Furthermore, sincethe SiO₂ is continuously fired during the film formation, a SiO₂ filmwith small leakage current and good dielectric strength can be formed.

Furthermore, in the above method of processing a surface, a noble gassuch as argon, xenon or the like having a mass number larger than thatof H₂O may be used as the second carrier gas so that energy loss of theheated H₂O molecules due to collision against molecules of the noble gascan be reduced and thus the H₂O molecules, without being cooled, canreach the reaction space near the object to be processed.

On the other hand, when a gas containing F₂ gas is used as the first gasand a gas containing H₂O is used as the second gas, the second gas, H₂O,can be selectively heated by microwave generated by the electromagneticwave generating unit, allowing selective etching of oxide films using HFanhydride rather than HF vapor.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

What is claimed is:
 1. A method of processing a surface of an object,comprising the steps of: supplying a first gas, unsusceptible to heatingby electromagnetic wave, through first gas supplying passages to nearthe surface of said object in an atmosphere under atmospheric pressure;separately supplying a second gas, susceptible to heating byelectromagnetic wave, through second gas supplying passages to near thesurface of said object; selectively heating only said second gas byirradiating said first gas and said second gas with electromagneticwave; and processing the surface of said object by reaction between saidfirst gas and said heated second gas.
 2. The method of processing asurface according to claim 1, wherein said selective heating step isperformed with said first gas and said second gas being separated fromeach other.
 3. The method of processing a surface according to claim 1,wherein said selective heating step is performed with said first gas andsaid second gas being mixed.
 4. The method of processing a surfaceaccording to claim 1, wherein said first gas contains a first reactivegas reacting on said second gas, and a first carrier gas not reactingwith said second gas, and wherein said second gas contains a secondreactive gas reacting on said first gas, and a second carrier gas notreacting with said first gas.
 5. The method of processing a surfaceaccording to claim 4, wherein said surface processing step includesforming a film on the surface of said object to be processed.
 6. Themethod of processing a surface according to claim 5, wherein said firstreactive gas is either a silane compound or an organosilane compound. 7.The method of processing a surface according to claim 6, wherein saidsilane compound is at least one material selected from the groupconsisting of silane, disilane, trisilane and dichlorosilane.
 8. Themethod of processing a surface according to claim 6, wherein saidorganosilane compound is at least one material selected from the groupconsisting of tetraethoxysilane, tetramethoxysilane,diacetoxydibutoxysilane, hexamethyldisiloxane, hexaethyldisiloxane,triethoxysilane and tetramethylcyclotrisiloxane.
 9. The method ofprocessing a surface according to claim 5, wherein said second reactivegas is H₂O.
 10. The method of processing a surface according to claim 1,wherein said electromagnetic wave is microwave.
 11. The method ofprocessing a surface according to claim 1, wherein said surfaceprocessing step includes etching the surface of said object to beprocessed.
 12. The method of processing a surface according to claim 11,wherein said first gas is F₂ gas and said second gas is H₂O gas.